NASA released this artist's rendering of NASA rover Opportunity on the surface of Mars. Opportunity landed on the red planet on Jan. 24, 2004 and is still exploring. Its twin Spirit stopped communicating in 2010.

The United States has some soul searching to do about its ambitions for space exploration. And it better do it before a new and potentially space-unfriendly administration takes over the White House next year.

That was the gist of Wednesday’s hearing hosted by the US House Committee on Science, Space, and Technology, where members questioned NASA’s direction and pushed for a concrete plan either for sending humans to Mars, an exceptionally expensive and technically challenging endeavor, or for exploring the Moon, a more affordable option.

“We have continual debate as to whether our goal should be the Moon, Mars or both,” said Tom Young, a former NASA director who testified at the hearing. “It is clear that we cannot do both and there is a need to focus all attention, capabilities, and resources upon one option.”

NASA has too little money, no roadmap of milestones, no clear goals, no details about the technology that needs to be developed to get humans to the surface of Mars or to the moon, and to stay there, complained committee members and some of the expert witnesses.

“We pretend that we are on a ‘#JourneytoMars,’ but in fact, possess neither the technology nor the economic resources necessary to undertake a human Mars mission now or within the foreseeable future,” testified Paul Spudis, senior scientist at the Lunar and Planetary Institute, a Texas-based space research institution.

Dr. Spudis argued that the country is missing an opportunity to explore the Moon, which is closer, cheaper, and is currently a target for exploration for Europe, India, Russia, and China.

NASA dropped its plans to explore the Moon in 2010, deciding instead to focus on asteroid exploration as a precursor to a mission to Mars. In 2015, the agency announced a $1.25 billion plan to send a solar-powered robot to an asteroid in 2020 to pluck a boulder off its surface, drop it in orbit around the Moon, and then send astronauts aboard a spacecraft called Orion, in development now, to the space rock in order to explore it.

But some space experts say that the asteroid exercise is futile and does not push technology far enough along to be of use to a future mission to Mars. A return to the Moon, said Spudis, would allow NASA to test the technologies, equipment, and procedures needed for future deep-space exploration. It would also keep the US competitive.

"As the world beats a path to the Moon, we stand aside. How can we claim leadership in a technological and scientific movement in which we have no participation and seek no ownership?” Spudis testified.

Elon Musk, the entrepreneur behind Tesla and SpaceX, said he will announce his plans to colonize Mars this year, and has already said that human missions could begin by 2025.

“I really think Elon Musk is going to be on Mars before NASA gets there,” said Rep. Dana Rohrabacher (R) of California at the hearing.

“Just a thought,” he offered.

A somewhat more fanciful project called “Mars One,” launched in 2012 by a Dutch nonprofit, plans to establish the first human colony there starting in 2020. More than 200,000 people answered the organization's call for volunteers to travel one way in order to start the Martian colony.

NASA’s specific plans for Mars might become more clear in the next year, as there is now a sense of urgency to create a definitive roadmap before a new presidential administration takes over and before NASA has to justify its budget in March, say the Democratic staff of the Science, Space, and Technology committee.

"Today the future of the human spaceflight program is far from clear," testified Mr. Young, the former NASA director, with "many pieces that are yet to be defined and funded."